While al Qaeda and the Muslim Brotherhood have become household names, another Sunni Islamist group of nearly equal importance--Hizb ut- Tahrir (HT), or the Islamic Liberation party--remains little known in the United States. That may be changing. HT's activities in places as far-flung as Britain, Germany, Indonesia, and the Palestinian territories have been cropping up in the news, and HT has lately entered the social networks of cyberspace, posting propaganda videos on YouTube to troll for recruits to its campaign for uniting Muslims worldwide in a new caliphate.

One of HT's goals is to destroy Israel and "liberate Palestine from occupation, racism and impurity by going back to the strict practice of a true Islam." In August, an HT rally in the West Bank city of Ramallah drew some 10,000 people under the banner "The caliphate, a force for the future." Although the man who founded HT in 1953 in Jerusalem, Sheikh Taqiuddin al-Nabhani, was a Palestinian--a qadi (Muslim judge) and an ex-Muslim Brother seeking a more radical alternative to the Brotherhood--HT was until recently an insignificant player in Palestinian politics. Not anymore. A Palestinian civil servant and HT adherent recently told the French daily Libération:

This year, thousands of Palestinians have joined our ranks, especially youngsters. They have had enough of democracy and its corruption, the Palestinian Authority infidels, and the fighting between Fatah and Hamas. They want the caliphate.

Although HT has no militia of its own and refrains from calling for armed struggle, it could always develop a military wing. Already, the sudden rise in the group's popularity, coupled with allegations of financing from Saudi princes, has become a source of concern for Hamas, Fatah, and the Israeli Shin Bet (the internal security service).

Indonesia is another place where HT is gaining popularity. On August 12, 100,000 people attended an HT meeting at the Bung Karno stadium in Jakarta to promote the idea of reestablishing the caliphate. The crowd chanted "Khalifah, Khilahah" ("Caliphate, creation" in Arabic) under a banner reading, "The Islamic caliphate rules the world." Back in 2000, HT's first Indonesian conference on this theme drew only a few thousand people.

In an interview published on August 18, Muhammad Ismail Yusanto, the leader of HT Indonesia, told Libération, "Capitalism is the worst system. It makes Muslims and non-Muslims alike suffer. To negotiate with global capitalism, you need to oppose to it another global system: the Islamic caliphate." To Yusanto the solution to the evils that accompany "Western influence and modernity" is simple: Impose sharia (Islamic law) on the country.

Like many Islamists, those of HT are busily using new technologies to spread their propaganda. A quite professional 45-minute video produced by HT Malaysia was recently posted on YouTube under the title "Oh Muslims--How Much Longer Can We Wait?" Although ostensibly historical, it is full of pseudo-facts. One heading, for instance, says, "2000: 'Israel' engages in the use of chemical weaponry" (note the scare quotes around Israel). Mainly, the video displays an endless succession of gory images of Muslim children killed or mutilated all over the globe. At one point, a Pakistani HT militant vows: "Until Khalifah returns, we will sacrifice our lives, our property and everything else." Another speaker states: "We say to the USA the flesh of the Muslims is not soft. . . . USA should know that what it has experienced in Falluja is the beginning of the end of its throne, tyranny, oppression, corruption and megalomania!" Even without an explicit summons to terrorism, the relentless violence of the images is incendiary, and suggestive messages such as "Oh armies of the Muslims, we wait for your help" abound.

The younger generation's pioneering spirit has made HTA one of the most innovative extremist groups in terms of its use of new media as a means of marketing its ideology. Some of their marketing schemes have included hip hop fashion boutiques, hip hop bands, use of online social networks, use of video sharing networks, chat forums and blogs.

Gruen warned that "HTA likely plays an important role in the global HT network due to its success in the new media arena and its access to international students, who study at American universities for several years before they return to their home countries."

How worried should the West be about the expansion of this not directly violent group, yet whose alumni include al Qaeda's notorious Khalid Sheikh Mohammed and Abu Musab al Zarqawi? Very worried, argues Maajid Nawaz, a former leader and recruiter for HT in Britain, the organization's headquarters. As Nawaz explained this month to the New York Times, "Hizb ut-Tahrir spearheaded the radicalization of the 1990s and cultivated an atmosphere of anger. . . . Buried in the literature is an ideology that inevitably leads to violence." Hudson Institute scholar Zeyno Baran put it best: "While HT as an organization does not engage in terrorist activities, it has become the vanguard of the radical Islamist ideology that encourages its followers to commit terrorist acts. . . . HT today serves as a de facto conveyor belt for terrorists."

In 2003, Germany joined most Middle Eastern countries in banning HT. But Germany, unlike the United States, outlaws hate speech and has no First Amendment. In the United States, as in Britain, HT has so far not met the criteria for banning as a terrorist group. Clearly, though, as it grows in numbers and in its presence on the web, it is pressing hard against the boundaries of what a free society can tolerate.

Olivier Guitta is a foreign affairs and counterterrorism consultant in Washington, D.C., and the founder of the newsletter The Croissant.